1. Field of the Invention
The present invention relates to audio systems connectable to portable audio players (also referred to as “portable music players”) that record audio files containing audio data of songs on an internal hard disk drive (HDD) or a semiconductor memory and that play back the recorded audio files to produce audio signals.
2. Description of the Related Art
Audio systems are connectable to portable audio players that record audio files of songs on an internal HDD or a semiconductor memory and that play back the recorded audio files to produce audio signals. As examples of such audio systems, the following audio systems are known (for example, see Japanese Unexamined Patent Application Publication Nos. 2002-175685 and 2006-48867). These audio systems include a connector for connecting to a portable audio player, a display device, an input device, and an audio output unit, such as a speaker and an audio amplifier. The audio systems receive user operations performed on the portable audio player connected to the connector through user interfaces, which are provided using the display device and the input device. The audio systems also cause the portable audio player to play back an audio file of a song instructed to be played back by a user using the user interface. In addition, the audio systems produce, from the audio output unit, an audio signal of the song that is supplied to the connector in response to the playback.
In addition, as a technique for such audio systems that handle audio files, an on-vehicle audio system that creates and stores a list of favorites in which audio files selected by a user from audio files stored in an internal HDD are registered and that allows a user to utilize the audio files using the list of favorites is known (for example, see Japanese Unexamined Patent Application Publication No. 2000-285660).
The following problems exist in an audio system connectable to a portable audio player when a user wishes to play back audio data in an audio file of a specific song among those stored in the portable audio player directly from a list of favorites or a keyboard shortcut of the audio system.
First, audio systems generally do not have direct access to a file system that manages audio files in portable audio players. Thus, the audio system may be incapable of loading an audio file of a song specified by a user into the audio system, or acquiring a path to the audio file of the song specified by the user on the file system. For this reason, the audio system cannot register audio files stored in the portable audio player in a list of favorites or a keyboard shortcut thereof and cannot handle the audio files directly.
Second, a plurality of portable audio players may be selectively connected to an audio system. An error may occur in the case that a list of favorites or a keyboard shortcut, which is created for one portable audio player, is executed when another portable audio player is connected to the audio system.